On 2 February 2016 at 13:49, David M. Lloyd <david.lloyd@redhat.com> wrote:

Ah okay, cool. This is an easy (and, in hindsight, rather obvious) enhancement that I can build into the new protocol with a minimum of effort.

Thanks!

On 02/02/2016 03:01 AM, Tom Jenkinson wrote:

Hi David,

I was referring to case 1 when the transaction is inflowed into a second
server. For JTS the type of transaction we create is a
ServerTopLevelAction and this in its ctor calls back to the remote server:
https://github.com/jbosstm/narayana/blob/master/ArjunaJTS/jts/classes/com/arjuna/ats/internal/jts/orbspecific/interposition/resources/arjuna/ServerTopLevelAction.java#L121
If the transport can do that without the TMs assistance then that works
for me :)

I don't think we should optimize for case 2. The incidents where a
transaction is created and not used should be really low.

Thanks,
Tom

On 1 February 2016 at 15:43, David M. Lloyd <david.lloyd@redhat.com
<mailto:david.lloyd@redhat.com>> wrote:

I was thinking about this a bit. It seems to me that there are two
"levels" of this that could be explored:

1. A transaction was made available to the server, but the EJB on
the server does not use the caller's transaction context, so the EJB
code never actually has to inflow the transaction. The EJB code
would be able to make this determination without any help from the TM.

2. A transaction was made available, and the EJB resumed it, but no
resources were actually enlisted, or perhaps resources were enlisted
but not actually used, resulting in the same effect but relying on
the TM to provide this information.

I guess when you refer to a callback from Narayana, (2) is what
you're referring to? When would this information be available?
Maybe as some special result of suspending the transaction?

On 01/29/2016 12:27 PM, David M. Lloyd wrote:

That's an interesting idea. So in effect, the remote EJB would
tell the
caller "you sent me a transaction ID, but in the end, I didn't
use it"?
I would need to think about how this might work in the
presence of
multiple concurrent invocations on the same transaction.

Either way though, I think it would still be beneficial for
clients to
be able to explicitly annotate a client method (or otherwise
establish a
policy) such that it causes transactions to be propagated (or
not), or
to enforce transaction-related preconditions. The interceptor that
implements this feature doesn't actually have protocol awareness: it
just examines the current environment, and decides whether to
attach the
transaction to the invocation context.

On 1/29/16 10:42 AM, Tom Jenkinson wrote:

One option that I would favour is to go down the JTS route
where the
subordinate calls back on the parent to tell it to register
it in the
transaction. This could be a new JBoss Remoting API that I
can invoke
from Narayana. The call would not necessarily be a remote
call, it would
invoke back into the JBR transport to tell it that when it
returns to
the parent it needs to enlist (or not).

On 29 January 2016 at 15:47, David M. Lloyd
<david.lloyd@redhat.com <mailto:david.lloyd@redhat.com>
<mailto:david.lloyd@redhat.com

<mailto:david.lloyd@redhat.com>>> wrote:

As you may know, WildFly supports a feature wherein an
EJB client
which
is invoking an EJB on a remote server has the option to
propagate its
local transaction to the remote server, treating the
remote server
as a
subordinate and coordinating the transaction's
two-phase commit among
the resultant graph of servers. This feature has
always been
limited in
that, when enabled, transactions are always propagated,
regardless of
the peer EJB's transaction policy, or of whether the
peer even has a
transaction manager.

So, for the invocation rework which I anticipate will
be included in
WildFly 11, I've introduced a new client-side
annotation intended
to be
associated with the EJB interface which informs the
client library
what
to do for transaction propagation for that interface.
In addition, I
intend to configuration strategies which will allow the
default
mode to
be specified in various ways (per-thread, globally, and
by target
interface/method all come to mind), for cases where the
EJB's remote
interface cannot be easily modified for some reason. I
expect to
also
broaden these configuration strategies to apply to all
client-side
EJB
interface/methods configuration items [3].

The first part of this change is the addition of a new
annotation
called
@ClientTransaction [1], which accepts as a value an
enum called
ClientTransactionPolicy [2]. The latter specifies
whether a local
transaction is required or forbidden for the method or
interface, and
also specifies whether the transaction is propagated or not
propagated.

I've added copious amounts of JavaDoc in order to establish
exactly what
the behavior of each mode is, as well as to specify how
each mode
interacts with the various modules that are configured
via the
standard
javax.ejb.TransactionAttributeType enum.

[1]

https://github.com/jbossas/jboss-ejb-client/blob/master/src/main/java/org/jboss/ejb/client/annotation/ClientTransaction.java

[2]

https://github.com/jbossas/jboss-ejb-client/blob/master/src/main/java/org/jboss/ejb/client/annotation/ClientTransactionPolicy.java

[2] (raw)

https://raw.githubusercontent.com/jbossas/jboss-ejb-client/master/src/main/java/org/jboss/ejb/client/annotation/ClientTransactionPolicy.java

[3] for a list, see:

https://github.com/jbossas/jboss-ejb-client/tree/master/src/main/java/org/jboss/ejb/client/annotation

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